<!DOCTYPE html>
<html lang="en" xmlns:v-on="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div id="app">
    <div v-if="count == 3">div1</div>
    <div v-else-if="count == 4">div2</div>
    <div v-else>div3</div>

    <hr>
    <div v-show="count == 3">div v-show</div>

    <br>

    <input v-model="count">
</div>

<script src="js/vue.js"></script>

<script>

    new Vue({
        el:"#app",
        data() {
            return {
                username:"",
                url:"https://www.baidu.com",
                count:3
            }
        },
        methods:{
            show() {
                alert("我被点击了")
            }
        }
        // data:function () {
        //     return {
        //         username:""
        //     }
        // }
    });

</script>

</body>
</html>